doc/org.texi: Update copyright year.

doc/org.texi

@@ -263,7 +263,7 @@
 @copying
 This manual is for Org version @value{VERSION}.
 
-Copyright @copyright{} 2004--2012 Free Software Foundation, Inc.
+Copyright @copyright{} 2004--2013 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document